Power control for boring machines



H. L. WALKER POWER CONTROL FOR BORING MACHINES Filed July 30 1921 13 Sheets-Sheet firaml. Walker @391 4 v w abtOT/MZZa/t 7% H. L. WALKER POWER CONTROL FOR BORING MACHINES May 6 1924; 1,493,301

Filed July 30. 1921 13 Sheets-Sheet 2 May 6 1924. 1,493,301

H. WALKER POWER CONTROL FOR BORING MACHINES Filed July so. 1921 13 Sheets-Sheet 5 um/whoa u firam Z. m M. m

May 6 1924.

H. L. WALKER POWER CONTROL FOR BORING MACHINES Filed July 50. 1921 13 ShetsSheet 4 unman H301,

V May 6, 1924.

H. 1.. WALKER POWER CONTROL FOR BORIN4G MACHINES Filed July 30. 1921 1s Sheets-Sheet 5 May a, 1924. 1,493,301 v H. L. WAL KER I POWER CONTROL FOR BORING MACHINES Filed July so. 1921 13 Sheets-Shed 6 avwe/ntoz firmZJlaM @513 M/flbtomw QM m. M

May 6 1924. I "1,493,301; H H. 1.. WALKER POWER CONTROL FOR BORING MACHINES 2 Filed July so. 1921 13 Sheetssheaf 7 a May 6 1924.

H. 1 WALKER POWER CONTROL FOR BORING MACHINES Filed July 30 1921 13 Sheets-Sheet 8 May 6 1924. 1,493,301

H. L. WALKER POWER CONTROL FOR BORING MACHINES M flbtom V 3513 344M 1%. m

May 6, 1924. 1,493,301

H. L. WALKER POWER CONTROL FOR BORING MACHINES Filed July so 1921 13 Sheets-Sheet 1o May 6 1924.

' H. L. WALKER POWER CONTROL FOR BORING MACHINES Filed July 50. 1921 13 Sheets-Sheet 11 May 6, 1924. 1,493,301

H. L. WALKER POWER CONTROL FOR BORING MACHINES v Filed July 30. 1921 13 Sheets-Sheet 12 l .1 7 l v163 182 w H l/ T '57 170 Y W May 6, 1924. I 1,493,301 7 H. L. WALKER POWER CONTROL FOR BORING MACHINES Filed July so. 1921 1s Sheets-Sheet 1 Patented May 6, 1924.

UNITED STATES PATENT'OFFIICE.

men n. WALKER, or cnavnnm, omo, assmnon. ro 0mm moron; can. O01;

rm, OF

CLEVELAND, OHIO, A GOBPOMTION OF OHIO.

POWER CONTROL FOB BOEING MACHINE.

Application filed an so, 1921. sea-m llo. 488,608.

To all whom it may concern:

Be it known that I, Hmam L. WALKER, a citizen of the United States, and resident of Cleveland, in the county of Cuyahoga and State of Ohio, have invented certain new and useful Im rovements in Power Controls for Boring achines, of which the following is a specification. I

The invention relates in general to a machine for causing a plurality of tools to function simultaneously and automatically in a timed cycle of succeeding operations and, specifically the invention relates to a self-controlled device for drilling, boring,

reamlng, facing and otherwise machining v V the bearings and bearing supports in a machined article where the parts to be ma- .chined are spaced apart in some definite preset relation, such for instance, as the aligned bearings in the crank casing of an automotive power plant.

Selecting for illustration the machining of the hearings in an automotive case fora detailed description of one situation where the invention is particularly applicable, it is noted thatin one form of such case it is Efiredthat' there be arranged in a preset e nite relation four sets of hearings or bearing supports with the axis of the bearings in each set: disposed accurately in alignment. These sets are disposed in ofi'set' relation and comprise three spaced apart cam shaft bearings; three spaced apart crank shaft bearings; three spaced apart water pump bearings and a generator shaft bearing. The completed machine, certain parts machine these hearings quickly in accurately preset alignment without vibratory movement and. without chattering action which might aifect the trueness of the alignment. These results are attained. in part by certain features of the machines described in my copending application, crank and cam shaft. line boring machines, Serial No. 425,315, filed November 20, 1920, and in part are attained by certain features of the tool control and tool actuating mechanism featured in this application. 7

One, of the prlmary objects of this invention is to provide a simple form of machine which, when once set in operation, will effect thenecessary boring, reaming and other machining operations without further attention 'on the part of the operator and which, at the same time will function in a manner to effect economy both in the lapsed time necessary to afl'ect the sequence of operations and which will incidentally effeet a saving in the power consumption necessary to dot-he required work The machine is of the type-in which the work tobe operated upon is disposed in fixed position in preset relation to the operating tools, andwith axially disposed sets of. these tools disposed to engage and operate on the work simultaneously from opposite sides thereof and in a preset time re lation. The present invention features a construction of such machines in which tool carryingheads can be moved rapidly to bring their tools into a position adjacent their machining positions and in which both the heads and their tools are caused to function at their approved working speed and ii the heads so governed that at-the completion of the machining operations the heads are rapidly moved with their tools into an inoperativeposition to permit the ready removal of the machined article and the replacement in the machine of another article to be machined.

Contributing to the objective for economy in lapsed time operation, another object of the invention is to provide an automatic control which may be readily varied to meet changes in conditions of the work operated upon, and which, when once set in operation, will complete its cycle of movement withoutfurther attention on the part of the operator and in. which every article will be machined exactly as every other article was machined.

Another object of the'invention, and feawhich will be sufficiently flexible in its mode of operation to'compensate automatically for small variations in the sizes of the difs 7 weasel ferent cases machined, and which work quietly and in a mannerto minimize shocks or vibration as the different movable parts I are brought to a stop or caused to change their direction of movements. I

In general the object of the invention as exemplified in the present disclosure is to provide a. simplified form of machine for accurately boring the several bearings in a crank case in the least possible time and to do this with a machine which features a number of movable parts compactly assembled into a machine which can be operated without the necessity of using skilled labor.

Various other objects and advantages of the invention will be in part obvious from an inspection of the accompanying drawings and in part will be more fully set forth in the following particular description of one form of mechanism embodying my invention, and the invention also consists in certain new and novel features of construction and combination of parts hereinafter set forth and claimed;

Referring to the accompanying draw FiguI-e 1 is a top plan view of a machine constituting a physical embodiment of the invention and with the work to be machined positioned thereon and shown in an irregular horizontal sectional view; a

Figure 2 is a view in front elevation of the machine shown in Fig. 1 with parts broken away and showing the work in vertical section.

Figure 3 is an enlarged vertical transverse sectional view taken on the lines 3-3 of Figures 1 and 2;

Figure 4 is a detail sectional view taken axially of the left head advancing shaft and taken on the line 4-4 of Fig. 3; Q

Figure 5 is a view similar to Fig. 3 taken on the lines 5-5 of Figs. 1 and 2;

Figure 6 is a detail sectional view taken. axially of'the main drive shaft at the right end thereof and taken on the line 6-6 of Fig. 5;

Figure 7 is a detail view partly in section of the left head advancing shaft and its spring coupling and cam control;

igure 8 is a transverse sectional view taken on the line 8-8 of Fig. 7;

Figur 9 is a view in front elevation of the head controlling valve as viewed from the plane indicated by the section line 9-9 of Fig. 2;

Figure 10 is an irregular sectional view of the head controlling valve taken on the line 10-10 of Fig. 9;

Figures 11 and 12 are each transverse sectional views taken respectively on the broken lines 11-11 and 12-12 of Fi 2;

Figure 13 is a horizontal sectiona view taken on the line 13-13 of Fig. 11;

Figure 14 is a top plan view of the cam bar and lever shown in elevation in Fig. 16;

Figure 15 is a horizontal sectional view of gear box and adjacent parts taken on line 15-15 of Fig. 12;

Figure 16 IS a detail view in elevation of the trip cam post and attached parts;

Figure 17 is an enlarged transverse sectional view taken on the line 17-17 of Fig. 13;

Figure 18 is an irregular sectional view taken on the line 18-18 of Fig. 17 showing the parts at the start of the machine;

Figure 19 is a view in end elevation of the pneumatic controlling slide valve;

Figure 20 is an irregular sectional view of this Valve taken on the line 20-20 of Fig.

19 and showing the normal position of the valves with the machine at rest;

Figures 21,22, and 23 are diagrammatic sections of the movable valves of Fig. 20 in the different succeeding positions and in which Fig. 21 shows the valve positions when the heads are rapidly advancing.

Figure 22 when the heads are slowly advancing with the tools rotating and Figure 23 when the heads are ontheir high speed retreat; and

Figure 24 is a diagrammatic view of the main parts of the machine spread out in one plane to facilitate an understanding of the relation of-the several parts.

I11 general it will be understood that the casing to be machined is first rough bored, and faced and then by replacing the boring tools with reaming or .finishing tools, the bores and the end faces are reamed and otherwise finished. In each cycle of operation there are three succeeding operations, first the heads at opposite ends of the machine are advanced rapidly toward the crank case the tools not rotating, and until the tools are within about 1 inch from the parts to be machined, second the heads are advanced slowly towards the crank case, the tools rotating and otherwise functioning and, third the heads with the tools not rotating are returned rapidly to their original position ready to have the cycle of operations repeated.

In the drawings and referring particularly to Figures 1 and 2 for a general description of the machine there is disclosed a table-like bed casting 25, the top 26 of which provides a support for the work A to be machined. In the present disclosure this work is one of the crank cases usual in automotive power plants and includes three cam shaft bearings lettered from left to right 15', b", 6, three crank shaft bearings 0', c", 0', three water pump shaft bearings d, d, d', and a single generating shaft bearing e, the several sets of multiple bearings being in alignment as is well known in such constructions.

bed casting and by two On top of the castingare four large projections 27 28, 29, 30 constituting too guiding members and which are accuratelylmed, bored and bushed with replaceable hard steel bushings and which constitute the guides in which the several boring bars andother tools rotate and slide while functioning to drill, bore, ream, face and otherwise machine the different bearin s.

The case to be machine is located in position on the top 26 by four steel pins 31 projecting upwardly from the top of the pilot pins 32 which project upwardly from t e members 28 and 29 and engage in recesses in the to of the case as shown in'Fig. 2. The era case is securely fastened in its located position by two clamps 33 carried by the members 2 and 30.

Large hollow brackets 34 and 35 are demountably bolted to opposite longitudinal ends of the casting 25 with their u per surfaces machined to form tracks 36 see Figs.

3 and 5) to form supports for longitudinally slidable heads 37 and 38, hereinafter referred to specifically as the left hand head 37 and-the right hand head 38. Each head is provided with a plurality of driving shafts which connect with tools carried in the adjacent guiding members 27 and 30.

Specifically describing the several tools and their driving connections with their respective heads, it is noted that the generator shaft bearing 0 is machined by a. generator.

shaft boring bar 39 guided in the projection 30, and driven from a shaft 40 mounted in the head 38 and hereinafter identified as a generator shaft. This shaft is coupled to the bar 39 by means of an Oldham coupling 41 which takes up any disalignment between the bar and shaft. It will be understood that in the following description of the several boring bars and their driving shafts in the heads all of the coacting drives are provided with these compensating couplings.

It is a feature of the machine disclosed that the machining tools for the several borings are guided in close proximity to the parts operated upon so as to minimize chattering and to eliminate any slight disaligning of the tools while in operation, and for this purpose the tools are supported inclose proximity to the parts to be machined. The outside bearings are machined from opposite sides of the casing, and the internal bearings, such as the bearings b" and c", are machined by means of tools 42 and 43 which are guided in the member 29 and are coupled to their driving elements in a manner more particularly described in my copending application above identified- Referring to Figs. 1, 2, 3 and 5for a description of the mechanism in the heads it. will be noted that each, of the heads'37 and 38 is provided with certain tool driving guided respectively in the adjacent projections 27 and 30. The left hand water pum boring bar 49 is guided in a separate gui ing member 50 at the back of the machine and the right hand water pump boring bar is guided in the projection 30. The shaft driving mechanism in the heads 37 and 38' are similar, except for obvious reversals in position and excepting for the presence of the generator shaft 40 in head 38 and which of course, is not present in head 37.

As shown in Figs. 3 and 5 the several shafts 40, 44, 45 and 46 are connected to be driven in unison by means of a gear train 51 so that all of the shafts, except the pump shaft 46 (Fig. 3) have an anti-clockwise movement in their machining operation. These gear trains are disposed in the upper parts 52 of the heads above their planes of support on the top of the brackets.

The gear trains 51 are connected to opposite ends of a main drive shaft 53 through a pair of bevel gear drives 54 (see Fig. 6) at opposite ends of upstanding shafts 55 journalled in bearings 56 forming internal projections from each of the heads.

The shaft 53 (see Fig. v13) is journalled at its center in a centrally positioned gear box 57 positioned within the casting 25 below thetop 26.- The shaft is adaptedto be driven from mechanism in the gear box and it is to be understood that a rotation of this shaft in one direction, indicated by the arrows in Figs. 3 and 5, will cause all of the tools to function in unison and at a speed dependent on ratio of the gears in the gear train 51.

In the operation of the machine the heads are both advanced rapidly from an inoperative position, withthe several tools clear of the case, into position with the tools adj acent their machining engagement with the casing. I This movement is provided bymeans of a pair of head advancing shafts,

a long nut 62 rotatably mounted in bearings 63 carried in. opposite ends 64 of the head.

'The nut "62r is held against longitudinal movement in its head by means of collars 65. 'The shafts 58 and 59 extend into opposite sides of the gear box and it will be understood that when the shafts are rotated by the mechanism-hereinafter described, in the gear box and with the nut held against rotation by means hereinafter described, the turning screw 61 acting on the held nut will cause the head controlled thereby to be advanced at high speed in either of its longitudinal directions depending upon the direction of rotation of the shafts.

The part of the main driveshaft in each head is operatively connected to the adjacent nut through a short auxiliary head driving shaft 66 which is journalled in the lower part of the head, and is connected to the shaft by means of a right angled spiral ear driving connection 67 and to the nut Y means of an endless spiral gear connection 68. From this construction it will be understood that the rotation of the main drive shaft in the direction indicated by the arrow in Figure 3 will drive through the shaft 66 to turn the nut at a time when the head advancing shaft is held by mechanism in the gear casing and thus cause the head to be advanced simultaneously with the actuation of the several boring bars and at a relatively slow feeding speed.

The main drive shaft 53 is provided, just outside the gear box (see Fig. 13), with a relatively small pinion 71 (see Fig. 12) constantly in mesh with the tooth portion 72 of a clutch drum 73, loosely mounted on a main power shaft 74 journalled in the gear box below the shaft 53. The main power shaft is connected on the opposite side of the gear box by means of gears 75 and 76 with a source of power herein indicated as an electric motor 77. It will be thus understood that the main power shaft 74 is rotating during the time that the motor is actively disposed and that the main drive shaft 53 is active only when clutched to the main power shaft. The clutch drum 73 (see Fig. 15) constitutes one element of a ring clutch and is designed to be coupled to the main power shaft by the engagement therewith of a coacting clutch element. 78. This latter element is secured by means of key 79 to the main power shaft 74 and is controlled in its movement to and from an operative position by means of a 'clutch rod 80 contained in the bore of the main power shaft and operatively controlled by a pneumaticallv actuated plunger 81 (see Fig. 15) hereinafter more fully described.

From Figures 13 and 24 it will be seen that the inner ends of each of the head advancing shafts 58 and 59 terminate within the gear box and are operatively connected to be driven in either direction from the main power shaft through a train of gears (see Fig. 15) which include gears 82, 83 and 84positioned exteriorly of the gear box and driving a secondary power shaft 85.journalled in the gear box. The shaft 85 has a sliding clutch 86 keyed thereto (see Fig. 18) and designed when moved in,one longitudinal direction, with a clutch gear 87-loosely mounted on i. e. to the right to clutch the secondary power shaft 85 and. when box. The gear 89 meshes with a clutch gear 1 91 which normally has a driving connection with a coacting clutch member 92 slidably mounted on and keyed to the right head advancing shaft 59. The clutch member 92 is controlled by a shifting rod 93 and is moved into its clutching position by a spring 94 acting on the plunger rod and is moved into an moperative position by a pneumaticalily controlled head 95 at one end of the r0 The clutch 86, when moved in the opposite direction to engage the clutch gear 88, drives through a train of gears 94, 95, 96 and 97. The gear 94 will be indentified hereinafter as a braking gear; the gear 95 is fixed to the shaft and the gear 97 drives the left head advancing shaft 58. It will be seen from this structure that both of the shafts 58 and 59 are rotating when the clutch 86 is in driving relation with either of the gears 87 or 88 and with the clutch member 92 completing the drive to the right head advancing shaft. With the member 92 in unclutched position the drive is confined to the left head advancing shaft and with the clutch 86 centered in neutral position both shafts 58 and 59 are idle. From the showing in the several figures it will be seen that the clutch 86 has two operative and one inoperative position, the neutral position shown in Figures 15 and 24 and the driving positions, one of which is shown in Figure 18 when the heads are advancing rapidly.

he clutch 86 is controlled by a honzontally disposed cam bar 98 resiliently connected by means of a. cam bar shaft 99 with the left head 37 as shown in F igures'2 and 7. The bar is provided with a cam recess 100, and extends into the leftside of the gear box, shown in Figures 13 and 14. An upstanding post 101 (see Figs. 11 and 16) is journalled in the gear box below and in advance of the free end of the cam bar. The post is provided at its upper end with a cam lever 102 (see Fig. 16) at the free end of which is ,a cam lever pin 1 03, moun'tcess is outlined by a starting pocket 104 leading from which tothe left is a longitudinal pin riding surface 105, followed in order by an inward incline 106, an inner riding surface 107,'a-nd a left end incline 108; then from left to right by a longitudinal riding surface 109 leading to a right end incline 110 leading to the starting pocket.

The post 101 has a three-arm trip cam 111 keyed thereto, as shown in Figure 18, with one of the arms 112 extending forwardly and fitted between collars 113 and 114 slidably mounted upon a valve shifting shaft 115 which is disposed parallel to and offset rearwardly below the secondary power shaft 85. A shifting member 116 is rigidly.

mounted on the shaft 115 and is provided centrally thereof with a fork 117 which engages in a peripheral groove 118 in the clutch 86 so as to move the same with the shifting of the valve shaft 115. The shifting member is provided at opposite ends thereof with upstanding catches 119 and 120 between each of which catches and the sleeve colla1s113 and 114 are disposed respectively coiled springs 121 and 122. The catches are disposed to coact with latches 123 and 124 which are pivoted on opposite walls of the gear box and are each provided on their underside with three stepped stops 125, 126 and 127 and are held in engagement with their respective catches by means of springs 128 and 129. The latches are lifted from their engagement with the catches by means of laterally extending arms 130 and 131 of the trip cam 111 which arms are designed to engage the adjustable heads 132 and 133 of the latches.

The machine is started by the pushing inof -a button 134 on the forward end of a push rod 135 which projects forwardly through an apron v136 defining the front of the casting 25. The rod 135 is connected by means of reach rods and levers 137 to a crank arm 138 on the post 101 so as to shift the cam lever 102 and thus shift the clutch 86 into a head drivingposition in a manner hereinafter more fullydescribed.

By means of the mechanism disclosed the heads are-advanced towards each other until an adjustable stop 139 on each head engages with a bumper post 140 on the adjacent faces of the projections 27 and 30, which thus limits the inward movement of the heads. It is obvious, however, that with the heads thus held the head advancing shafts 58 and 59 working in the nuts 62 will continue to rotate and thus tend to pull the shafts from the gear box. This is avoided by permitting the shafts to elongate for the required continued movement of the head advancing shafts. The shafts are of two parts and as shown in Figure 7 the parts are connected by means of a spring coupling 141. This permits the separation of the shaft parts at 142 compressing the coupling springs 143 as the shafts are being drawn through the screw nuts in the heads, and the spring coupling will reunite the shaft parts on the rerotation of the head advancing shafts on the retreat of the heads to their initial positions. I

In order to sto the advance'of the shafts 58 and 59 an a justable nut 144 is U fixed to the shaft 58 and is caused at the end of. 1ts permitted movement to bear against the upper end of a lever 145. The opposite lower end of this lever engages against an adjustable nut 146 fixed to the cam bar controlling shaft 99 to shift the cam barf" 98 into position to react on; the cam lever and thus to shift the clutch 86 in a direction to cause the heads to be rapidly retreated into their initial positions. A spring 147 on the shaft 99 restores the cam bar to its clutch pneumatic 152 which, when air pressure is introduced therein, causes the rod 81 to shift to the left and in a direction'to cause the clutch to function, and similarly the other head and cylinder form a main clutch release pneumatic 153 which when energized acts to release the clutch.

' The shifting rod 93 controlling the connection of power with the right head advanoing shaft 59 is moved into clutching position by the spring 94 and in the opposite or unclutching direction by a head drive disconnecting pneumatic 155 formed by the plunger head 95 working in a cylinder 154 formed in one side of the gear box.

There is disposed in the path of retreat of the right hand head 38 a head controlled valve containing member 156 (see Fig. 10)

mounted in the right hand bracket 35. The

member houses a normally closed valve 157 at one end of a plunger 158 which projects towards the head. The valve is seated'by a.

spring 159 and the connection with the plunger is such that the valve is unseated by the engagement therewith of the head 38 in its retreat into its position for receiving the work in place on the work support.

Compressed air is'provided from a suitable supply reservoir 160 (see Fig. 24) supplied by a compressor 161, from which lead two supply pipes, one of which 162 leads to one side of the valve 157' and the other of which 163 leads to an inlet 164 in a valve casin 165 mounted on the left side of the gear ox (see Fig. 15). The valve casing is provided with another compressed air inlet 166 which is in communication by means of a pipe. 167 with the opposite side of the valve 157 from the pipe 162. It will be seen from this connection that the inlet 164 is always open to a source of compressed air while the inlet 166 is open to the compressed air only when .the head 38 is at the outer limit of its retreat from the work.

The valve casing v165 is of cylindrical open end form, is provided with two exhaust ports 168 and 169. The bore of the valve Casing isfitted with a bearing sleeve 170 drilled diametrically to provide peripheral by-passes for connecting the several inlets and exhausts with the pneumatics hereinbefore described. Mounted within the sleeve are two barrel valves, an outervalve 171 fixed to a reduced end of the valve shaft 115 and movable therewith and an inner follower valve 172 slidably mounted on the valve shaft and having a limited freedom of movement between the outer valve and a shoulder 173 formed on the valve shaft. The

' valve casing is provided with three longiis disposed with reference to the inlet 163 so that when the valves are tudinally spaced apart outlets, the one nearest the gear. box and numbered 174 leading,

by means of pipe 175 to the main clutch release pneumatic 153; the second outlet 176 which is bifurcated and leads by means of a pipe 17 7Ito the main clutch actuating pneumatic 152 and by means of a pipe 178 to the brake pneumatic 179 controlling the gear 94.

The third outlet 180 leads by means of a pipe 181 .to the head drive disconnecting pneumatic 155. It is understood that all of the inlet and outlet pipes are controlled by suitable pet cocks 182. H

The follower valve is provided with 21 peripheral recess 183 which in one position, as shown in Figure 20, connects the inlet 164 withthe main clutch release pneumatic and in another position connects this pneumatic with the exhaust 169 as shown in Figures 21 and 22. The outlet 176 leading to the brake and to the main clutch actuating pneumatic separated, as shown in Figure 22, the pneumatics 179 and 155 are directly opened to the pressure, at the inlet 164. The outer valve 171 is provided with a similar recess 184 of a length such that when the valves are in their normal position, shown in Figure 20, the head drive disconnecting pneumatic 155 is opened to the exhaust 168 and when in the position shown in Figure 23*the inlet 166 controlled bythe valve head is opened to the head drive disconnectingpneumatic. 7

In operation and assuming that the case Ato be machined is located in clamped position onthe work, support, that the proper tools are position, that the clutch 86 is in its neutral position, and that the parts are otherwise intheirnormal position as shown in the diagrammatic View (Figure 24) and that the valves are in their normal position shown in F i function. T 1e operator thenv pushes in the button 134. This shifts the cam lever pin 103 into the pocket 104 int-he cam bar so that it will ride along the straight edge 105 so as to apparently take tions, indicated bv the arrowed dotted circles shown in 'Figure 14. This movement of the post 101 causes the trip cam to push on the sliding collar 114 moving the same to are 20 the machine is ready to the succeeding pos1-- the right compressing the spring 122 on that side.

This initial movement of the starting mechanism will have the effect of causing the righthand catch 120 to be engaged by the stop shoulder 126 120 from movement to the right, and atthe same time will cause the spring 122 to be placed under tension until the movement of the arm 131 acting on the head 133 is sufliwhich holds the catch 55 cientto lift the latch 124 against the tension of the spring 129. Releasing the shoulder 126 from the catch 120 permits the member 116 to be snapped to the right. This action shifts the clutch 86 to the right and into the position shown in Figure driving connection between the shaft 85 and the gear clutch 87.- This will cause the gear train formed by the gears 87, 89, and 91 to drive the right head advancing shaft 59 and 18 to form a 95 to drive through the shaft 90 and the train formed by the gears 95, 96 and 97 to drive the left head advancing shaft 58. These, shafts 58 and 59 will then coact to move the heads rapidly towards the work, but as the main drive clutch 73-78 at this time is in inoperative position, the maindrive shaft gear 72 is not rotated and therefore the main or tool driving shaft 53 is not rotated.

As the left head 37 moves to the right it movement continues until the incline 106 is brought into engagement with the pin 110. 1 he incline 106 is disposed in such position that it will act on the pin 103 to shift the pushes before it the cam bar 58 and this 110 lever 102 into the full line position shown in Figure 14* and thus cause the trip cam 111 to react on the sleeve 113 in a right to left movement (see Fig. 18) to compress the spring 121 and thus snap the clutch 86 into neutral position at a time when the machinmg tools are in close proximity, about a; quarter of an inch to the parts to be machined. .This has the effect, 'of course, of disconnecting the power from the head advancing shafts 58 and 59.

During the advance of the heads the pneumatic controlling valves are in the position shown in Figure 21 at which time the pneumatics are all free of pneumatic pressure.

As the clutch 86 is shifted into its neutral position at the end of the rapid advance of the heads the outer valve 171 is shifted into the position shown in Figure 22. It will be ioted from this Figure 22 that the pneumatic pressure. at the inlet 164 is acting through the pipe 178 on the pneumatic 179 which is interposing a frictional resistance to the rotation of the gear 94 and thus acts to secure the head advancing shafts 58 and 59 against rotation. At the same time the pneumatic pressure admitted to the'pipe 177 is acting on the main clutch pneumatic to shift the.

same to the left and into a position to cause the movable element 78 of the clutch to effect a driving connection between the main power shaft and the main drive shaft 53. The rotation of the main drive shaft acts through the ar trains 51 in the oppositely disposed heaifs to rotate the several tool driving shafts, and acts through the auxiliary shafts 66 to turn the nuts 62 on the held screws. The advance of the heads towards the work is thus continued but at the proper relatively slow feeding speed necessary to cause the boring bars to function. As the left hand shaft continues to advance it pushes the cam bar with the pin 103 riding along the edge 107 until the cam bar reaches the incline 108. The incline 108 acts through the cam lever 102, and shifts the clutch 86 into driving engagement with the gear clutch 88 thus causing the head advancing shafts to beagain rotated but in the opposite direction to the direction in which they were rotating to advance the heads towards the work.

It may so happen, however, that either one, or both, of the heads have reached their stopped positions by the engagement of the stop 139 with the bumper post 140 prior to the engagement of the incline 108 with the cam lever pin, but this will merely mean that the shafts will separate at the points 142 as previously described.

During the retreat of the heads into their original positions the cam pin rides along the surface 109 and as the incline surface 110 engages the pin it shifts the cam lever 102 and reacts through the trip cam 111 to reset the clutch into its neutral position, separated from both of the gears 87 and 88.

During this retreat the valves are in the position shown in Figure 23. in which position the follower valve provides open com m'unication between the air pressure at the inlet 164 and the main clutch releasing pneumatic. The outer valve is at this time in position to provide communication between the inlet 166 leading from the head valve 156 and the head drive disconnecting pneumatic 95.

The gear ratios actuating through auxil iary head driving shaft 66 are so designed that when advancing the heads, the tools of both heads have finished their boring op-v eration at the same time, and in returning to their starting position the righthand head 38 reaches its stopping place 'sooner than the head 37.

When the head 38 reaches its stopping place it engages the plunger 158 and acts thereon to open the valve 157 thus permitting the passage of air pressure through the inlet 166, and pipe 181, to the head drive disconnecting clutch 95, which moves the element 92 to the left of the position shown in Figure 24 and thus disconnects the driving gear 91 from the right head advancing shaft 59. This, of course, stops shaft 59 from rotating but allows shaft 58 to continue rotating until stopped by the action of the cam bar shifting the clutch 86. When the trip cam acting through the shaft 115 restores the parts to their normal position the valves are reset to exhaust the pneumatic 155 thus permitting the spring 94 to restore the clutch element 92 into its normal driving position.

This completes the cycle of operation and with proper substitution of tools the cycle may be repeated on the work or the work may be replaced with another piece and the operation repeated. It will be understood that the only manual actuation necessary after the work is mounted is the pressing of the button 134 at the front of the machine and the work is machined and the parts automatically restored to their normal inactive position independent of any further action on'the part of the operator.

By means of a' device of the class described, it is possible to design the bearings for the tools in accurately positioned relation to each other and to the support for the work, thus insuring the accurate machining of the different bearings and every casing machined will be a replica of every other casing so machined. Due to the close positioning of the part of the work to be machined to the guides and supports for the tools, tool chattering has been practically eliminated and the parts coact to insurean even, smooth, non-vibratory movement 'of the tools. The several bearings have been made as long as is physically possible thus providing a rugged connection between the several movable parts, and the sliding connection between the several parts tends to feature smoothness of operation of the machine as a whole. This smoothness of operation is further attained by the use of the pneumatics for controlling the several shifting devices and these pneumatics have been used wherever such control is possible. The grouping of the valve parts for controlling the pneumatics into one casing permits the.

localizing of the valves, thus facilitating ready inspection, cleaning and replacing of the valvular parts of the organization. The several pneumatics are disposed so that ready access-may be provided thereto from 

